[PATCH] opp: convert dev_warn() to dev_dbg() for duplicate OPPs

[Viresh Kumar]

Giving a warning in case we add duplicate OPPs doesn't workout that great. For
example just playing with cpufreq-dt driver as a module results in this:

$ modprobe cpufreq-dt
$ modprobe -r cpufreq-dt
$ modprobe cpufreq-dt

cpu cpu0: dev_pm_opp_add: duplicate OPPs detected. Existing:
freq: 261819000, volt: 1350000, enabled: 1. New: freq: 261819000, volt: 1350000,
enabled: 1
cpu cpu0: dev_pm_opp_add: duplicate OPPs detected. Existing:
freq: 360000000, volt: 1350000, enabled: 1. New: freq: 360000000, volt: 1350000,
enabled: 1
cpu cpu0: dev_pm_opp_add: duplicate OPPs detected. Existing:
freq: 392728000, volt: 1450000, enabled: 1. New: freq: 392728000, volt: 1450000,
enabled: 1
cpu cpu0: dev_pm_opp_add: duplicate OPPs detected. Existing:
freq: 454737000, volt: 1550000, enabled: 1. New: freq: 454737000, volt: 1550000,
enabled: 1

This happens because we don't destroy OPPs (created during ->init()) while
unloading modules.

Now the question is: Should we destroy these OPPs?

Logically kernel drivers *must* free resources they acquired. But in this
particular case, the OPPs are created using a static list present in device
tree. Destroying and then allocating them again isn't of much benefit. The only
benefit of removing OPPs is to save some space if the driver isn't loaded again.

This has its own complications. OPPs can be created either from DT (static) or
platform code (dynamic). Driver should only remove static OPPs and not the
dynamic ones as they are controlled from platform code. But there is no field in
'struct dev_pm_opp' which has this information to distinguish between different
kind of OPPs.

Because of all this, I wasn't sure if drivers should remove static OPPs during
their removal. And so just fixing the reported issue by issuing a dev_dbg()
instead of dev_warn().

Reported-by: Stefan Wahren <stefan.wahren at i2se.com>
Signed-off-by: Viresh Kumar <viresh.kumar at linaro.org>
---
 drivers/base/power/opp.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
index 89ced95..490e9db 100644
--- a/drivers/base/power/opp.c
+++ b/drivers/base/power/opp.c
@@ -466,9 +466,9 @@ int dev_pm_opp_add(struct device *dev, unsigned long freq, unsigned long u_volt)
 		int ret = opp->available && new_opp->u_volt == opp->u_volt ?
 			0 : -EEXIST;
 
-		dev_warn(dev, "%s: duplicate OPPs detected. Existing: freq: %lu, volt: %lu, enabled: %d. New: freq: %lu, volt: %lu, enabled: %d\n",
-			 __func__, opp->rate, opp->u_volt, opp->available,
-			 new_opp->rate, new_opp->u_volt, new_opp->available);
+		dev_dbg(dev, "%s: duplicate OPPs detected. Existing: freq: %lu, volt: %lu, enabled: %d. New: freq: %lu, volt: %lu, enabled: %d\n",
+			__func__, opp->rate, opp->u_volt, opp->available,
+			new_opp->rate, new_opp->u_volt, new_opp->available);
 		mutex_unlock(&dev_opp_list_lock);
 		kfree(new_opp);
 		return ret;
-- 
2.0.3.693.g996b0fd